Injection nozzle tester



Jan. 14, 1964 c. TAYLOR 3,117,444

INJECTION NOZZLE TESTER Filed April 24, 1961 3 Sheets-Sheet 1 f gi 57 PP2a B g M A ttorneys Jan. 14, 1964 c. l. TAYLOR 3,117,444

' INJECTION NOZZLE TESTER Filed April 24, 1961 5 Sheets-Sheet 2 InventorCECIL 1:. TAYLOR ttorney;

Jan. 14, 1964 c. 1. TAYLOR INJECTION NOZZLE TESTER 3 Sheets-Sheet 5Filed April 24, 1961 v Inventor detail. I. TAYLOR M Attorney;

United States Patent F 3,117,444 INEEGTION NQZZLE TESTER Cecil IsaacTaylor, Buckingham, England, assignor to Leslie Hartridge Limited,Buckingham, England, a

British company Filed Apr. 24, 1961, Ser. No. itliilil Claims priority,application Great Britain Apr. 27, B60 3 Ciaims. (til. 73-11?) Thisinvention relates to testing apparatus for the injection nozzles ofcompression ignition internal combustion engines. Such apparatusnormally comprises a manually operated pump by which liquid (usuallyfuel oil of the type used in the engines) is compressed and suppliedthrough a duct to the injector to be tested, there being a pressuregauge connected to the injector to indicate the pressure at which theinjector needle lifts to open the injector.

The conventional injector used in internal combustion engines comprisesa body adapted to be mounted in the engine having an injection nozzlemounted at its end, the latter penetrating into the engine cylinder. Thenozzle consists of a nozzle body containing a valve seat and one or moreorifices through which the fuel is injected, and a needle having aconical valve portion which seats itself on the seating formed in thenozzle body. In use the needle is acted upon by a powerful spring whichkeeps it in position on the seating. When pressure is applied to thenozzle it acts on the portion of the valve cone above the seating andwhen the pressure rises above a predetermined level it lifts the needle,whereupon some of the fuel oil is forced past the seat and through theinjection orifice or orifices. This lowers the pressure in the nozzlebody and the needle tends to seat again. If the pressure is maintainedat a high level (as when the pump piston is moving at high speed) thenthe needle is held open and the pressure is governed by the restrictionimposed by the injection orifices, but if the pump piston is movingslowly en the escape of fuel allows the needle to fall back upon theseat, when the pressure again rises to lift the needle. The injectorthus opens and closes very rapidly, and makes a buzzing noise. A goodinjector should buzz well.

In testing and setting nozzles information is required on four points,some of which are inter-related. The first is whether the needle makes afluid-tight joint with the seating or whether it is leaky; the second isthe amount of leakage between the needle diameter and the bore in thenozzle body in which it is located; the third is whether it will buzzwell (a leaky nozzle will not buzz very well); and the fourth is thefuel pressure at which it will open. Information on the first point maybe obtained by subjecting the nozzle to a fuel pressure just below thatat which it will open, for a short period. If the seating is leaky thena droplet of fuel collects on the end of the nozzle. If such leakagetakes place while the injector is operating in the engine the fuel whichleaks is converted to carbon so that a thick deposit of carbon quicklybuilds up on the nozzle body and this interferes with the etficientoperation of the engine. Assuming that the needle makes a fluid-tightjoint on the seating, the leakage along the needle diameter may also bedetermined by applying a pressure just below the needle opening pressureto the 3,.lll/i i4 Fatented Jan. 1d, 1964 "ice nozzle body and thenholding the pump piston still. The rate at which the pressure in thesystem leaks away is a measure of the leakage along the needle diameterbut since some fuel also leaks past the pump piston the test is notreliable in the kuownapparatus. If the leakage in the nozzle body isexcessive then, in normal operation, the rate of pressure rise at eachinjection is slower than it should be and this again interferes withthe, satisfactory operation of the engine.

The buzz" test is carried out by operating the pump very slowly so thatthe injector needle is allowed to reseat itself after each ejaculationof fuel oil. In the known apparatus the rapid fluctuations in pressureat the injector cause jerky movement of the pump lever.

The setting of the opening pressure is carried out by operating thepumpextremely slowly, so that the pressure is gradually raised to theinjector opening pressure, and noting the reading on the pressure gaugeat which the needle lifts to allow an injection of fuel. It is mostimportant that the pump should be operated slowly, and even so there isdifliculty in noting the pressure reading because, as already mentioned,the pressure drops as soon as the needle opens. If the pump lever isoperated a little too quickly then the pressure rises too rapidly to theopening pressure and the pressure gauge needle flies back and juddersbefore the operator has been able to note its reading, so that he isleft in doubt as to the exact pressure at which the nozzle opened.

One object of the present invention is to provide apparatus in which theabove-mentioned tests may be carried out with certainty by a relativelyunskilled operator.

Another object is to provide a simple and reliable injector testingapparatus.

A further object is to provide an injector testing apparatus in whichtwo adjustable needle valves are provided, connected respectivelybetween the pump and the injector and the injector and the pressuregauge, whereby the accurate testing and setting of injectors isfacilitated.

Further objects and advantages of the invention will become evident froma reading of the following description of one form of apparatusaccording to the invention, having reference to the accompanyingdrawings in which:

FIGURE 1 is a front elevation of an injector nozzle tester;

FIGURE 2 is a sectional side elevation of the tester of FIGURE 1;

FIGURE 3 is a plan view of the tester of FIGURE 1;

FIGURE 4 is an enlarged ghosted view of the control Valve block in thetester; and

FIGURE 5 is a side view of an injector support bracket showing aninjector in position.

Referring to the drawings, the tester comprises a base 11, provided withlugs 12 by which it may be fixed to a bench, and a casing 13 forming asuperstructure on which the controls, instruments and a hood for theinjector nozzle under test are mounted. Contained in the base 11 is ahigh pressure pump comprising a cylinder 14, suitably attached to thebase, cooperating with a piston 15 which is urged by a spring 16 to itsouter position. The piston 15 has an extension 17 which is acted upon byan arm 18 of a bell crank, the other arm 19 of which has a lever 2dattached to it, terminating ina ball end 21. The bell crank is pivotedon a pin 22 supported in lugs 23 and 24 which are integral with the base11. The bell crank has 3 a third arm 25 having a fiat end which engagesa face 26 on the base 11, the engagement limiting the outward movementof the piston under the influence of the spring 16. The outlet 27 of thepump is connected by a pipe 28 to a block 29 which is shown in moredetail in FIGURE 4 and will be more particularly described hereafter.For the present it will sutfice to mention that fuel pumped through thepipe 23 passes through a first restrict-or valve to an outlet from theblock 2" and thence to the injector under test by a pipe 39. Theinjector is supported on a bracket (not shown in FIGURES l, 2 or 3 butshown separately in FIGURE 5) bolted to facings 55 on the base. Theinjector is surrounded by a hood 31 to prevent the injector spray frombeing distributed over a large area. At the rear of the hood 31 is anextractor fan 5 to remove the spray and since the finely divided spray,intimately mixed with air, is highly inflammable the extractor fan isdriven by an air-turbine 57 because an electric motor might producesparks. The turbine 5'7 is supplied with compressed air through a pipe53 and is controlled by means of a rotary control valve 65 mounted onthe casing 13. The extractor, being of a centrifugal type also acts tocondense the fuel oil, which is then returned through a pipe (not shown)to a reservoir 59 built into the base, from which it is supplied to thepump cylinder 14 through a duct 6%). The reservoir is initially lledthrough a filler cap 61.

Fuel supplied to the block 2?, after passing through the firstrestrictor valve, may also pass through a second restrictor valve andinto a pipe 32, which leads to a pressure gauge 33 mounted on thesuperstructure 13. The hood 31 includes an upper domed portion 34containing a lamp, controlled by a switch 35, which may be switched onwhen desired in order to obtain a better view of the spray or anydroplets which may form at the nozzle end during the seat leakage or dryseat test.

Above the pressure gauge 33 is a stop clock 36 which may be started andstopped by a lever 3'7 and set to zero by means of a button 38. The stopclock enables the time required for the pressure to fall from one levelto another (leakage test) or the time during which pressure ismaintained, to be accurately determined.

The control block 29 previously referred to comprises, as shown inFIGURE 4, an inlet connection by which fuel oil from the pump may besupplied via the pipe 28 to a needle type restrictor valve 39,co-operating with a seating as. The needle valve is connected to ascrewthreaded stem 41 having a knob 42 at its end, the screwthreadedstem passing through a nut 53 attached to the block A pointer 44 isattached to the knob 42 and cooperates with a graduated scale 45(FIGURE 1) by which the setting of the needle valve 39 may bedetermined.

Fuel oil passing through the needle valve 39 enters a duct 46 in theblock 29 which communicates with the pipe 3% leading to the injector.The pipe Ell is held in position on the block 29 by a fitting 47, andits other end is connected to a fitting 62 which passes through thecasing l3. A further pipe 66 (FIGURE 5) is connected between thelast-mentioned fitting and the injector on test. The bracket fitted tothe facings and the pipe connection to the injector must, of course, besuited to the particular injector being tested and several types may benecessary to cover all the different kinds of injector which may requiretesting. A typical bracket is shown in side view in FZGURE 5 andconsists of a base portion 67 and a support portion 68 which carries aplate of suitable size and shape to accept an injector body 69 andnozzle '70 to be tested.

Fuel oil in the duct 46 also passes a second needle valve 48co-operating with a seating 49. The needle valve 48 is controlled by asecond threaded stem 5% similar to the stem 41 and is operable by asecond knob 51 similar to the knob The threaded stem 50 passes through anut 52, similar to the nut 43. Fuel oil passing the valve l enters aduct 53 which is connected to the pipe 32 (shown dotted in FIGURE 4)leading to pressure gauge 33.

When an injector is to be tested it is mounted in the tester and thepump, consisting of piston 15 operating in cylinder 12-, is actuated bymoving the lever 2% down wards, when fuel oil is forced into the block29 and through the block to the pressure gauge and the injector. Byscrewing down the needle valve 3? to the appropriate degree arestriction is imposed on the flow of fuel oil from the pump such thatthe operator is compelled to operate the lever 29 slowly. Consequentlythe pressure at the injector rises slowly.

In order to carry out a dry seat test the pump pressure is raised to alevel just below that at which the injector would normally open and theneedle valve 39 is then screwed down completely, to close it. in thisway the pressure in the system is trapped and it is easy to note whetherthe needle seat leaks and allows a droplet of fuel oil to form on theend of the nozzle. if no such leakage takes place in a prescribed timethen the needle valve 3? may be re-opened slightly while the pressure isrestored to the original figure, by operation of the pump, and theneedle valve 39 is again closed, the stop clock 36 being started at thesame instant. The operator watches the pressure gauge until the pressurefalls by a predetermined amount and then stops the clock 3-6. He thenhas an accurate record of the rate of leakage along the injector needlediameter, since this is related to the time which has been recorded.

To carry out the buzz test the restrictor valve 39 is set to impose asubstantial restriction on flow. The operator is thus compelled to movethe pump lever slowly and the rapid fluctuations of pressure at theinjector do not cause jerky movement of the pump lever.

To set the injection pressure the restrictor valve 39 is set to analmost closed position and the pump is operated to raise the pressure upto the injection pressure. Since the pressure at the injector rises veryslowly it is possible to see the exact pressure reading at which theinjector needle lifts to allow injection, and appropriate adjustents aremade to the injector spring to set the injector to the desired openingpressure. The pointer 4-4, in conjunction with the graduations 45,facilitate the accurate setting of the valve 39.

During all these operations the flow of fuel oil to and from thepressure gauge 33 may be controlled by operation of the needle valve 48by means of the knob 5. For example, during the dry seat and leakagetests the needle valve d8 may be opened to such an extent that thepressure gauge follows the injector pressure instantly. During the buzztest the needle valve 43 is preferably closed because the Bourdon tubein the pressure gauge would not only be subjected to violent pressurefluctuations which might cause damage to it, but its flexibility willgive rise to pressure waves which may interfere with the test.

When the injector opening pressure is being tested the needle valve 43is preferably set to an almost closed position so that the pressuregauge needle accurately follows the very slow rise in pressure butcannot follow the sudden drop in pressure when the injector needleopens. This not only helps to prevent damage to the pressure gauge butenables the operator to see more clearly the exact pressure at which theinjector opens.

I claim:

1. Apparatus for testing injectors and injector nozzles of compressionignition internal combustion engines comprising a base, a hand-operatedpump mounted in said base, a casing on said base, a pressure gaugemounted on said casing, two manually-operable restrictor valves in avalve block supported on said casing, a support for an injector andnozzle to be tested carried on said casing, a duct in said blockcommunicating with one side of each of said restrictor valves, a pipeconnecting said duct to said injector, a pipe connecting said pump tothe other side of one of said restrictor valves, and a further pipeconnecting said pressure gauge to the other side of the other of saidrestrictor valves.

2. Apparatus as claimed in claim 1 comprising a lamp incorporated insaid hood to illuminate said injection nozzle during test.

3. Apparatus as claimed in claim 1 comprising a pointer on at least oneof said restrictor valves co-operating with graduations whereby thesetting of said one restrictor valve is indicated.

References Cited in the file of this patent UNITED STATES PATENTS

1. APPARATUS FOR TESTING INJECTORS AND INJECTOR NOZZLES OF COMPRESSIONIGNITION INTERNAL COMBUSTION ENGINES COMPRISING A BASE, A HAND-OPERATEDPUMP MOUNTED ON BASE, A CASING ON SAID BASE, A PRESSURE GAUGE MOUNTED ONSAID CASING, TWO MANUALLY-OPERABLE RESTRICTOR VALVES IN A VALVE BLOCKSUPPORTED ON SAID CASING, A SUPPORT FOR AN INJECTOR AND NOZZLE TO BETESTED CARRIED ON SAID CASING, A DUCT IN SAID BLOCK COMMUNICATING WITHONE SIDE OF EACH OF SAID RESTRICTOR VALVES, A PIPE CONNECTING SAID DUCTTO SAID INJECTOR, A PIPE CONNECTING SAID PUMP TO THE OTHER SIDE OF ONEOF SAID RESTRICTOR VALVES, AND A FURTHER PIPE CONNECTING SAID PRESSUREGAUGE TO THE OTHER SIDE OF THE OTHER OF SAID RESTRICTOR VALVES.